Dreams are a form of thinking activity in the human brain. In the process of social activities, human beings have to touch many things around the world, some of which are seen with their own eyes, some of which are heard with their own ears, some of which are told by people around them, some of which are from movies, some of which are from pictures and texts. Images of these things are stored in some nerve centers in the cerebral cortex. When people sleep, most nerve centers are in a state of inhibition, but some nerve centers are still in an excited state. A lot of stored information is processed synthetically, and some processed contents are stored in the nerve center, which can be recalled completely when you wake up. This is a dream. In different states before going to sleep, the completeness of memories is different. Because the information stored in each nerve center is different, the dreams formed by nerve activities are also different, bizarre and unimaginable.
Dreams are not reality, but a part of nerve centers in the cerebral cortex are incomplete and inaccurate, which is not necessarily the result of comprehensive processing of actual information, so we can't reason, judge or explain anything on this basis. This won't be a sign.